Hicon HDR2500
1. Ensure no DVD is in the tray
2. Enter 0 0 8 6 0 0 0 (the final 0 makes it multi-region)
3. Press Enter
You may need to try this a few times, but it will work. Once successful, a '0' will appear on your screen next
press the power button on the remote. Then you can use any region dvd in the machine.